I want push and post a text to next screen when tapping on Button. But NavigationLink need @state property to catch data. How to avoid this? I hope there is a way I only handle data in button action. Swift @State var selection: Int? = nil   @State var text: String? = nil       var body: some View {     VStack(content: {       HStack(alignment: .center, spacing: nil, content: {         NavigationLink(destination: Drawing(text: text), tag: 1, selection: $selection) {           Button("complete", action: {             print(self.selection)             print(self.text)             self.text = "hello"             self.selection = 1           })         }       }).padding()

Sometimes I need restrict the painting area in a PKCanvasView. I have tried mask the layer of PKCanvasView and it work fine. Swift let mask = CAShapeLayer() mask.path = cgPath canvasView.layer.mask = mask But sometimes it is difficult to get the cgPath. I get the rect and maskImage by use floodfill, how to clip canvas context in PKCanvasView? Swift context.clip(to: rect, mask: maskImage)

When I use png, iOS system will automatically cache it in memory after decoded. So if I use the image in two UIImageView of different frame sizes, iOS system only need to decode it once. But if I use svg icon in different sizes of UIImageView, whether each time is to re-parse the svg data to draw and render. So it is not recommended to use svg, especially for more complex graphics picture, right?